1. Field of the Invention
The present invention relates to a fuel tank mounting device with which an industrial use vehicle such as a forklift is provided, specifically to a fuel tank mounting device with which the look-behind easiness for the operator of the vehicle can be ensured when the fuel tank is fixed to the vehicle, the mounting/dismounting work as to the fuel tank can be performed in a simple manner with a one-step operation when the fuel tank is replaced with a newly charged fuel tank, and the tank replacement workability is extremely enhanced, and to an industrial use vehicle with the fuel tank mounting device.
2. Background of the Invention
There are some industrial use vehicles that are driven with fuel gas such as LPG (Liquefied Petroleum Gas). As an example of such vehicles, a forklift driven with fuel gas is shown in FIG. 8; whereby, the forklift 50 is provided with: the body frame 51 on which a seat 52 that the operator sits on is placed; a head guard 53 that is placed over the seat 52; a mast 54 that is placed on the front side of the body frame so as to be able to tilt; a fork 55 that is supported by the mast so as to freely ascend and descend along the longitudinal direction of the mast; a counterweight 56 that is provided on the rear side of the body frame so as to strike a balance between the front side weight and the rear side weight regarding the forklift body in response to a load lifting condition. In a conventional industrial use vehicle of this kind, a tank fixing mechanism (a tank mounting mechanism) 58 for fixing a fuel tank 57 charged with compressed fuel gas is usually provided so that the fuel tank 57 is fixed to the forklift over the counterweight 56 or on the head guard 53, on the rear side of the vehicle; thus, the fuel is supplied from the fuel tank 57 toward an engine room of the forklift, the engine room being placed at an area below the seat 52.
The conventional tank mounting mechanisms have a configuration whereby the upper face of the counterweight forms a substantially flat surface; the fuel tank is fixed to a bracket 58 placed on the upper face of the counterweight by use of at least one fixing band; and the axis direction of the fuel tank is placed along a direction perpendicular to the fore-and-aft direction of the vehicle. Further, when the fuel tank A is replaced by a newly charged fuel tank B, the bracket to which the fuel tank A has been fixed is made to slide into the rear side, so that the fuel tank can be removed from the vehicle namely from the bracket. Still further, in another conventional way, when the fuel tank A is replaced by the tank B, the bracket to which the fuel tank A has been fixed is made to slide toward the rear side, and a hinge rotation axis is formed by an edge of the bracket so that the bracket together with the fuel tank is rotated about the hinge rotation axis and the tank is lowered toward the ground whereby the tank can stand upright in order to be removed from the bracket.
The patent reference 1 (JP2003-118990) discloses a configuration whereby a concave shape (seen from the rear side as depicted FIGS. 1-3 of the reference) is formed in the counterweight so that the upper face of the counterweight is lowered, and the left and right end areas of the counterweight protrude upward; a tank fixing means for fixing the fuel tank placed between the left and right end protruding areas of the counterweight comprises a sliding mechanism by which the tank is made slide fore-and-aft and vice versa, and a lowering/lifting mechanism for lowering the fuel tank A from a laterally laid condition (an upper home position) to a vertically hung-down condition (a lower home position) and lifting the fuel tank B from the vertically hung-down condition to the laterally laid condition. The reference lays stress on the following points; according to the disclosure, due to the lowered upper face of the counterweight, the field of the operator's vision toward the back way in the rear can be prevented from being hindered by the fuel tank; and, due to the provided tank fixing means and the lowering/lifting mechanism, the replacement work as to the fuel tank can be easily performed.
As described thus far, the conventional fuel tanks are fixed to the vehicle over the counterweight or on the head guard, so as to be installed on the rear side of the vehicle; the fuel tanks are placed at a remarkably higher position beyond the upper face of the counterweight; thus, when the operator while sitting on the seat looks behind, the field of the operator's vision is hindered by the fuel tank. In this way, there has been a problem in ensuring the look-behind easiness. Especially in a case where the fuel tank is made slide backward and the tank fixing means for fixing the fuel tank is placed on the counterweight of the vehicle rear side so as to reduce the slide distance, the look-behind easiness is further spoiled.
According to the device disclosed by the patent reference 1, the look-behind easiness can be improved to some extent; however, since the tank replacement work includes the steps of making the tank slide backward, rotating the tank and the supporting bracket thereof about an horizontal axis, and placing the tank in an upright attitude, the replacement work is complicated. Further, since the device itself for performing this replacement work becomes complicated and the replacement work of heavy tanks has to be often performed, there is apprehension about problems.
In addition, for the conventional fuel tank dismounting device whereby the fuel tank is made slide toward the rear side direction when being dismounted for the replacement, the weight of the counterweight must be taken into consideration; namely, the counterweight needs to be weighty. In this regard, the length of the counterweight along the fore-and-aft direction of the vehicle has to be long enough to ensure the weight. Therefore, in the conventional fuel tank mounting/dismounting device, there has been a difficulty that the slide distance is lengthy, the tank replacement workability is spoiled, and the mounting/dismounting device itself becomes large.
Moreover, in the conventional fuel tank dismounting device whereby the fuel tank is hung down by a rotation mechanism in an upright attitude after being made slide toward the rear side direction, there has been a difficulty in dismounting/mounting the fuel tank in/from the upright attitude, since there is a large space between the bottom face of the fuel tank and the ground, when the tank with the bracket is placed in the upright attitude.
On the other hand, as is often the case with a conventional industrial use vehicle, the seat for the operator needs to be made slide forward or the back of the seat needs to be reclined when the cover of the engine for the vehicle has to be opened so that the maintenance work as to the engine is performed; nevertheless, the counterweight of the conventional vehicle hinders this engine maintenance work. In this way, the engine maintenance work has to accompany the movement as to a configuration element such as the seat thereby the position thereof needs to be shifted forward so as to fully open the engine cover. Thus, there has been a problem that the maintenance work requires much expense in time and effort.